reetesh nigam wrote:
> Hi All,
>
> I am retrieving data from Sybase database using Sybase module of Python.
> My query is not taking time however fecthall is taking longer time.
>
> Below is the test script :
>
> def run_query(db,query): ## Run query and resturn record result
> t1 = datetime.now()
> cursorObj = db.cursor()
> t2 = datetime.now()
> cursorObj.execute(query)
> t3 = datetime.now()
> import pdb
> pdb.set_trace()
> rowset = cursorObj.fetchall()
> t4 = datetime.now()
> cursorObj.close()
> print "Time taken to make cursor --%s"%(t2-t1)
> print "Time taken to execute query --%s"%(t3-t2)
> print "Time taken for fetchall--%s"%(t4-t3)
> return rowset
>
> Output:
> Time taken to make cursor --0:00:00.000037
> Time taken to execute query --0:00:00.379443
> Time taken for fetchall--0:00:14.739064
fetchall() probably has to transfer a lot of rows. If you want to process
them one at a time you can turn run_query into a generator
def run_query(db, query):
...
while True:
row = cursor.fetchone()
if row is None: break
yield row
...
A complete implementation that guarantees that the cursor is closed might
look like this (untested):
@contextlib.contextmanager
def run_query(db, query):
cursor = db.cursor()
try:
cursor.execute(query)
yield iter(cursor.fetchone, None)
finally:
cursor.close()
# use it
with run_query(db, query) as rows:
for row in rows:
print row
This is likely to *increase* the overall time taken, but should drastically
reduce the time you have to wait for the first record to be printed, i. e.
the latency.
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